Within the categories of homogeneous and heterogeneous mixtures there are more specific types of mixtures including solutions, alloys, suspensions, and colloids. A solution is a mixture where one of the substances dissolves in the other.
Weathering and erosion. Weathering is the process where rock is dissolved, worn away or broken down into smaller and smaller pieces. There are mechanical, chemical and organic weathering processes. Organic weathering happens when plants break up rocks with their growing roots or plant acids help dissolve rock. Once the rock has been weakened and broken up by weathering it is ready for erosion. Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind or gravity. Mechanical weathering physically breaks up rock. One example is called frost action or frost shattering. Water gets into cracks and joints in bedrock.
Water causes much erosion. When it falls as acid rain, it can dissolve rocks that are sensitive to acid. Marble & limestone weather when exposed to the rain. LEACHING by ground water: water soaks into the soil, picks up chemicals. This allows the water to leach or dissolve rocks it comes in contact with at bedrock. WAVE ACTION at the beach: the waves tumble rocks. The action of waves on a beach causes much erosion. The waves pound on the rocks & over time, cliffs crumble.